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hey guys,

my roadmaster cooling fans start when the temp needle is about half way(the temp gauge)

due to hot weather, i want them to start running on the first quarter (when the water temp is about 80 degrees Celsius ( observed at the climate control)

is it possible to program it through the climate control and/or how?

and what is the best water temp. range does the car need for warming the engine up in winter?

:)
 

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hey guys,

my roadmaster cooling fans start when the temp needle is about half way(the temp gauge)

due to hot weather, i want them to start running on the first quarter (when the water temp is about 80 degrees Celsius ( observed at the climate control)

is it possible to program it through the climate control and/or how?

and what is the best water temp. range does the car need for warming the engine up in winter?

:)
80C is 176F which would be too low. Fans would run all the time as that is the normal running temp as read thru the RM CC. Are you in Canada? Put car, year and location in your signature info.

I like primary to start about 185, secondary about 190.........other users will differ. Amazing how little they actually run with AC off even in hot weather. Key is to have a well maintained cooling system.

You can not program thru the CC - must use a program either by you on a laptop thru OBD port or send out the PCM - tons of threads on this subject.
 

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"I like primary to start about 185, secondary about 190..."

That is good if you are using a 160 degree thermostat. Alex programmed mine at about that when I changed it. A 180 degree thermostat starts to open at 180 and your running temps are around 195-200. If you have the 180, they will run all the time at those temps.
Try somthing like 200 and 205. That is substantially lower than the stock settings.
 

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"I like primary to start about 185, secondary about 190..."

That is good if you are using a 160 degree thermostat. Alex programmed mine at about that when I changed it. A 180 degree thermostat starts to open at 180 and your running temps are around 195-200. If you have the 180, they will run all the time at those temps.
Try somthing like 200 and 205. That is substantially lower than the stock settings.
Exactly right. I should have expanded my post. I do use the 180 thermostat. The CC on the RM reads the lower of the 2 temp sensors.

So when it indicates 175 (my normal running indicated temp), it is really 190 - 195, etc. which would be thermo fully open and leaves some latitude before the fans would come on.
 

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… what water temp range does the car need for warming the engine up in winter?
My winter cooling system settings:

180°F/82°C Thermostat [fully open by 196°F/91°C]
Primary Fan ON 203°F/95°C
2ndary Fan ON 212°F/100°C

My winter operating temps are between 194°F/90°C [highway cruising] and 214°F/101°C [parked, engine idling at least 20 mins, needle never goes past 2/3 to the right].
Those settings are fine for summer use too, if you don't prefer colder summer settings. (I prefer and use colder summer settings.)

Once the engine [coolant] reaches 194°F/90°C, my passengers stop complaining about waiting for heating.
 

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Good post Marky as always. But OP has a RM and he is reading from the climate control which are not the same readings you have. 15-20F lower. Somewhere there is a good thread on this subject.
 

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Good post Marky as always. But OP has a RM and he is reading from the climate control which are not the same readings you have. 15-20F lower. Somewhere there is a good thread on this subject.
80 Celsius (176 Fahrenheit) is the warmer sensor. The other sensor is about 20 degrees cooler. You can read them both. The Celsius one is correct.
 

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I've access to TWO readings at all times:
the head temp sender which reports a relative reading to the instrument panel
the CTS, which informs the PCM, which tells the fans when to turn on and off.
Is the RoadMaster Climate Control relaying
a. [water pump] Coolant Temp Sensor readings
b. [head] Coolant Temp Sender-IP readings
c. (what could 'c' be? Never owned a RoadMaster …)
From the RM sticky I linked above:

Here are the most common you will need to know

-00 PCM diagnostics codes
-01 CCM Diagnostic trouble codes
-02 HVAC Diagnostic trouble codes
-03 SIR Diagnostic trouble codes
-04 ABS/TC Diagnostic trouble codes
-06 Engine RPM
-08 Coolant Temp (°F) - Reading taken at Cylinder head sensor, typically 20* cooler than the -24 reading
-14 Vehicle speed
-24 Coolant Temp (°C) - Reading taken at the Water Pump sensor, This is what the PCM uses to control the fans.


It shows the 2 temp readings - one in F and one in C - so you have apply the formula 9/5 x C + 32 = F to be consistent. Would have made more sense to use the same scale.

So do you have 2 temp gauges, a switching arrangement, or what?

Big thanks to MillerTimeGS for getting me back to reality.
 

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So do you have 2 temp gauges, a switching arrangement, or what?
My IP displays head temp, as it should.

I've also owned an AutoXray for GM OBD1 vehicles since my 1st 9C1-LT1 in 1998, which displays the H2Opump temp (unlike DataMaster, it only shows ONE thing at a time, so I have to scroll to it).

Hmmm … why DOES the engine PCM run off the H2Opump's Coolant Temp Sensor, rather than the temp of the head?
 
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